Coating device, and coating method using said device

ABSTRACT

A coating device is provided which has a bar which coats a coating liquid on a strip-shaped body conveyed in a given direction, and a dam-shaped member disposed at an upstream side of the bar so as to face the bar. Also provided is a coating method which, in the coating device, supplies the coating liquid from between the dam-shaped member and the bar so as to carry out coating. A flow rate of the coating liquid passing through a gap between the strip-shaped body and the dam-shaped member is set to be 3 m/min or more. A flow rate of the coating liquid passing through a gap between the bar and the dam-shaped member is set to be 5 mm/sec or more.

This is a divisional of application Ser. No. 10/458,383 filed Jun. 11,2003.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority under 35 USC 119 from Japanese PatentApplications No. 2002-170894 and No. 2002-178116, the disclosure ofwhich is incorporated by reference herein.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates to a coating device and a coating method.In particular, the present invention relates to a coating device and acoating method in which, even when coating a highly viscous coatingliquid onto a strip-shaped body while conveying the strip-shaped body athigh speed, local absence of the coating liquid due to the accompanyingair which is brought in together with the strip-shaped body does notarise.

Moreover, the present invention relates to a coating device and acoating method in which, in a coating device which has a bar which coatsa coating liquid on a strip-shaped body conveyed in a given directionand a dam-shaped member disposed at the upstream side of the bar, caneffectively prevent problems at the coated surface which are caused bystuck matter which arises at the dam-shaped member at the upstream side.

2. Description of the Related Art

A planographic printing plate undergoes processes as follows to befabricated. Commonly, at least one face of an aluminium web formed ofpure aluminium or an aluminium alloy is dressed. Then an electrolyticoxidation layer is formed at that face as necessary, and thus a supportweb is formed. Next, a platemaking layer-forming liquid, such as aphotosensitive layer formation solution, or a heat-sensitive layerformation solution, is coated onto a surface at the side of the supportthat has been dressed and is dried, and a photosensitive orheat-sensitive platemaking layer surface is formed.

Generally, a bar coater is employed for coating a coating liquid, suchas a photosensitive layer formation solution, or a heat-sensitive layerformation solution, at a belt body, such as the aforementioned supportweb.

Conventionally, this bar coater is generally equipped with a bar and acoating section. While the bar is in contact with a lower surface of acontinually running web, the bar rotates in a direction the same as therunning direction of the web, or a direction opposite thereto. While theweb is running, the coating section discharges the coating liquid at anupstream side from the bar, relative to the running direction of theweb, and forms a coating liquid pool, thus coating the coating liquidonto the lower face of the web. The upstream side relative to therunning direction of a web is hereafter referred to simply as “theupstream side”.

The bar coater may be a bar coater disclosed in Utility ModelRegistration No. 2,054,836 includes a dam plate which is provided inproximity with a bar at the upstream side of the bar, and is formed suchthat thickness at an upper end portion thereof becomes thin toward adownstream side in the running direction of the web. The upper endportion of the dam plate curves toward the bar, and includes a flat facewith a length of 0.1 to 1 mm at a peak portion thereof. Another barcoater may be one disclosed in Japanese Patent Application Publication(JP-B) No. 58-004589, which includes a first dam plate which is formedsuch that thickness at an upper end portion thereof becomes thinnertoward a downstream side. This bar coater is also provided with a seconddam plate at the downstream side of the bar. The downstream side in therunning direction of a web is hereafter referred to simply as “thedownstream side”.

When the running speed of the support web becomes higher, an entrainedair layer, which is a film of air that follows along and runs with thesupport web, that is, entrained air, is formed at the surface of thesupport web.

In either of the above-described bar coaters, when an entrained airlayer is formed at the surface of the support web, the entrained airlayer is carried into the coating liquid pool. As a result, the coatingliquid is not applied to the surface of the support web uniformly, andcoating of the coating liquid is not carried out stably, causing filmdiscontinuities.

When the flow rate of the coating liquid which flows out from the gapbetween the bar and the dam plate is low, the flow of the coating liquidwhich overflows from the dam plate to the upstream side is intermittent,and is not uniform along the direction in which the dam plate extends,i.e., the widthwise direction of the strip-shaped body which is passingabove the dam plate.

Accordingly, at the upstream side edge portion at the dam plate, thephenomenon of drying and sticking arises in which the coating liquid,which has adhered to the dam plate, dries out and sticks thereto. Thestuck matter which arises due to this drying and sticking is a cause ofvarious problems in surface quality at the coated surface on which thecoating liquid is coated, such as coating streaks which are stripe-likedefects, the adhesion of stuck matter in which the stuck matter comesoff of the dam plate and adheres to the coated surface, and the like.

SUMMARY OF THE INVENTION

A object of the present invention is to provide a coating device and acoating method which can carry out stable coating without problems suchas local absence of the coating liquid at a coated film or the likearising, even in cases in which coating is carried out while astrip-shaped body such as a support web or the like is traveling at ahigh speed of an extent such that an accompanying air film is formed onthe surface.

In the present invention, stuck matter which sticks to the dam-shapedmember does not arise even in cases in which the flow rate of thecoating liquid discharged out from between the bar and the dam plate islow. Accordingly, another object of the present invention is to providea coating device and a coating method in which problems with the surfacequality, such as coating streaks or the like, do not arise.

A first aspect of the present invention is a coating device having a barwhich coats a coating liquid on a strip-shaped body conveyed in a givendirection, and a dam-shaped member disposed at an upstream side of thebar so as to face the bar. The coating device carries out coating bysupplying the coating liquid from between the dam-shaped member and thebar. A flow rate of the coating liquid passing through a gap between thestrip-shaped body and the dam-shaped member is set to be 3 m/min ormore.

In this coating device, a portion of the coating liquid supplied frombetween the dam-shaped member and the bar toward the strip-shaped bodyis coated onto the strip-shaped body. The remainder of the coatingliquid passes through the cap between the dam-shaped member and thestrip-shaped body, and flows down toward the upstream side of thedam-shaped member.

The flow rate of the coating liquid flowing through the gap toward theupstream side is set to be 3 m/min or more. Therefore, the accompanyingair, which is brought into the coating device together with thestrip-shaped body, is pushed to return toward the upstream side, i.e.,is eliminated. Accordingly, such accompanying air is not brought intothe coating device.

Accordingly, even in cases in which the conveying speed of thestrip-shaped body is raised, local absence of the coating liquid causedby accompanying air does not arise, and a uniform coated surface can beobtained.

The bar may be smooth bars with surfaces which are even. The bars mayalso be, for example, grooved bars in which circumferential directiongrooves are formed, wire bars at whose surfaces metallic wires withdiameters of around 0.1 mm are wound to a certain pitch or are tightlywound.

Belt bodies have continuous belt forms and include base materials havingflexibility. Specific examples include, besides a support web mentionedabove, base materials which are employed in photosensitive materials,magnetic recording materials. Abase material may be, for example, theaforementioned support web, a base material for a photographic film,baryta paper for photographic printing paper, a base material for anaudio recording tape, abase material for a video tape, or a basematerial for a floppy disk. Alternatively, metallic thin plates employedfor coated metallic plates, such as a color steel sheet, can be used.

Besides a platemaking layer-forming liquid mentioned in the “Descriptionof the Related Art”, the coating liquid may be a photosensitive agentcolloid solution employed for forming a photosensitive layer for silversalt photography, a magnetic layer formation solution employed information of a magnetic layer of the above-mentioned magnetic recordingmaterial, various coating materials employed for undercoat layers,intermediate coating layers, and overcoat layers of the above-mentionedcoated metallic plates.

In the present invention, at the time of coating, the gap between thestrip-shaped body and the dam-shaped member may be 0.1 to 3 mm.

In a coating device in which the gap is set in this way, even when thecoating liquid is supplied at the usual liquid feed amount at a barcoater, local absence of the coating liquid caused by the bringing-in ofaccompanying air can be particularly effectively prevented because theflow rate of the coating liquid passing through the gap between thestrip-shaped body and the dam-shaped member is set to 3 m/min or more.

In the present invention, a pressing roller, which presses thestrip-shaped body toward the bar, may be provided at the upstream sideof the dam-shaped member.

In a coating device provided with such a pushing roller, the size of thegap between the strip-shaped body and the dam-shaped member at the timeof coating can be increased or decreased by increasing or decreasing thepressing force of the pressing roller. Thus, the gap can easily becontrolled to a size corresponding to the supplied amount of the coatingliquid.

In the present invention, the bar may be able to rotate at acircumferential speed which is different than the conveying speed of thestrip-shaped body.

In a coating device having such a structure, a stable pool of thecoating liquid is formed by the space between the strip-shaped body andthe bar and the dam plate. Thus, the coating liquid can be coated evenmore uniformly and stably.

In the present invention, the bar may be able to rotate at acircumferential speed which is equal to the conveying speed of thestrip-shaped body.

In a coating device having such a structure, the bar can be made to beslave-driven by the strip-shaped body. Thus, a bar driving device forrotating the bar can be omitted.

In the present invention, the bar may be able to rotate in a directionopposite to the conveying speed of the strip-shaped body.

In a coating device having such a structure, a stable pool of thecoating liquid is formed by the space between the strip-shaped body andthe bar and the dam plate. Thus, the coating liquid can be coated evenmore uniformly and stably.

A second aspect of the present invention is a coating method which coatsa coating liquid onto a strip-shaped body conveyed in a given direction,by using a coating device having a bar which coats the coating liquidand a dam-shaped member which is disposed at an upstream side of the barso as to face the bar. The coating method comprises the step of carryingout coating with a flow rate of the coating liquid passing through a gapbetween the strip-shaped body and the dam-shaped member being set to be3 m/min or more.

In accordance with this coating method, for the same reasons asdescribed above, even in cases in which the conveying speed of thestrip-shaped body is raised, local absence of the coating liquid causedby accompanying air does not arise, and a uniform coated surface can beobtained.

A third aspect of the present invention is a coating device having a barwhich coats a coating liquid on a strip-shaped body conveyed in a givendirection, and an upstream side dam-shaped member disposed at anupstream side of the bar so as to face the bar. The coating devicecarries out coating by supplying the coating liquid from between theupstream side dam-shaped member and the bar. A flow rate of the coatingliquid passing through a gap between the bar and the upstream sidedam-shaped member is set to be 5 mm/sec or more.

In this coating device, the flow rate of the coating liquid passingthrough the gap between the upstream side dam-shaped member and the baris set to be 5 mm/sec or more. Therefore, a uniform flow of coatingliquid, which flows over the upstream side dam-shaped member toward theupstream side, is continuously formed.

Accordingly, no drying and sticking arises at the upstream sidedam-shaped member. Therefore, the occurrence of problems in surfacequality, which are caused by stuck matter which is formed due to thisdrying and sticking, is prevented.

A fourth aspect of the present invention is a coating device having abar which coats a coating liquid on a strip-shaped body conveyed in agiven direction, an upstream side dam-shaped member disposed at anupstream side of the bar so as to face the bar, and a downstream sidedam-shaped member disposed at a downstream side of the bar so as to facethe bar. The coating device carries out coating by supplying the coatingliquid from between the upstream side dam-shaped member and the bar. Aflow rate of the coating liquid both at a primary side clearance whichis a gap between the bar and the upstream side dam-shaped member, and ata secondary side clearance which is a gap between the bar and thedownstream side dam-shaped member, is set to be 5 mm/sec or more.

In this coating device, not only the flow rate of the coating liquid atthe primary side clearance, but also the flow rate of the coating liquidat the secondary side clearance, is set to be 5 mm/sec or more. Thus, auniform flow of the coating liquid is formed continuously at thedownstream side dam-shaped member as well.

Accordingly, the occurrence of drying and sticking is prevented at thedownstream side dam-shaped member as well. Therefore, in the presentcoating device, the occurrence of problems in surface quality, which arecaused by this drying and sticking, is prevented even more effectivelythan in the coating device of the first aspect.

In the present invention, the gap between the bar and the upstream sidedam-shaped member may be set to be 0.1 to 10 mm.

In a coating device in which setting is carried out in this way, evenwhen the coating liquid is supplied at the usual liquid feed amount, thegeneration of stuck matter at the upstream side dam-shaped member andthe downstream side dam-shaped member, and the occurrence of problems insurface quality accompanying such generation of stuck matter, can beeffectively prevented because the coating liquid flows through theprimary side clearance and the secondary side clearance at a flow rateof 5 mm/sec or more.

In this coating device, the upstream side dam-shaped member and thedownstream side dam-shaped member may be fixed with respect to the bar.However, if the upstream side dam-shaped member and the downstream sidedam-shaped member are formed so as to be able to approach and move awayfrom the bar, by moving the upstream side dam-shaped member and thedownstream side dam-shaped member, the primary side clearance and thesecondary side clearance can be enlarged when the discharged amount ofthe coating liquid is high, and the primary side clearance and thesecondary side clearance can be reduced when the discharged amount ofthe coating liquid is small. Accordingly, in this coating device,regardless of the discharged amount of the coating liquid, it is easy tomaintain the flow rate of the coating liquid at 5 mm/sec or more at theprimary side clearance and the secondary side clearance.

In the third and fourth aspects of the present invention, the bar may beable to rotate at a circumferential speed which is equal to theconveying speed of the strip-shaped body.

In a coating device in which setting is carried out in this way, the barcan be made to be slave-driven by the strip-shaped body. Thus, a bardriving device for rotating the bar can be omitted.

In the third and fourth aspects of the present invention, the bar may beable to rotate at a circumferential speed which is different than theconveying speed of the strip-shaped body.

In a coating device in which setting is carried out in this way, astable pool of the coating liquid is formed by the space between thestrip-shaped body and the bar and the dam plate. Thus, a coated filmwhich is even more uniform is formed.

In the third and fourth aspects of the present invention, the bar may beable to rotate in a direction opposite to the conveying speed of thestrip-shaped body.

In a coating device in which setting is carried out in this way, astable pool of the coating liquid is formed. Thus, a coated film whichis even more uniform is formed.

A fifth aspect of the present invention is a coating method which coatsa coating liquid onto a strip-shaped body conveyed in a given direction,by using a coating device having a bar which coats the coating liquidand an upstream side dam-shaped member which is disposed at an upstreamside of the bar so as to face the bar. The coating method comprises thestep of carrying out coating with a flow rate of the coating liquidpassing through a gap between the bar and the upstream side dam-shapedmember being set to be 5 mm/sec or more.

For the same reasons as described in connection with the third aspect ofthe present invention, in accordance with this coating method, it ispossible to prevent stuck matter from arising at the top portion of theupstream side dam-shaped member, and prevent the occurrence of problemsin surface quality caused by such stuck matter at the coated surface ofthe strip-shaped body.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram showing the structure of one example of acoating device relating to the present invention.

FIG. 2 is an enlarged view showing the structure of a vicinity of a barin the coating device shown in FIG. 1, and showing an interval between astrip-shape body and a dam-shaped member.

FIG. 3 is an enlarged view showing the structure of the vicinity of thebar in the coating device shown in FIG. 1, and showing an intervalbetween the dam-shaped member and the bar.

DETAILED DESCRIPTION OF THE EMBODIMENT

The basic structure of one example of the coating device relating to thepresent invention is shown in FIG. 1. The structure of the vicinity of abar in the coating device is shown in FIG. 2.

A coating device 100 relating to the present embodiment is a coatingdevice which coats a liquid for forming a plate-making layer on aroughened surface Sg of a support web W which travels continuously alongthe direction of arrow a in FIG. 1. The support web W is one example ofthe strip-shaped body in the present invention. The liquid for forming aplate-making layer is one example of the coating liquid in the presentinvention.

As shown in FIG. 1, the coating device 100 has, beneath a conveyingplane T which is a conveying path of the support web W, a bar 2 which isdisposed orthogonal with respect to the traveling direction of thesupport web W, and a supporting stand 4 which is a plate-shaped memberwhich supports the bar 2 from beneath. At the upstream side, in thetraveling direction a, of the supporting stand 4 and the bar 2, thecoating device 100 has an upstream side dam-shaped member 6 which isprovided parallel to the bar 2 and so as to oppose the bar 2 and thesupporting stand 4. Moreover, at the downstream side, in the travelingdirection a, of the supporting stand 4 and the bar 2, the coating device100 has a downstream side dam-shaped member 8 which is provided parallelto the bar 2 and so as to oppose the bar 2 and the supporting stand 4.The upstream side dam-shaped member 6 corresponds to the dam-shapedmember in the coating device of the present invention. A V-shaped barholding groove 4A, which holds the bar 2, is provided in the top surfaceof the supporting stand 4, at which top surface the bar 2 is held. Thedam-shaped members 6, 8 may be plates.

The distance between the upstream side dam-shaped member 6 and the bar 2may be about 0.1 mm to 3 mm.

Further, as shown in FIG. 2, the interval between the support web W andthe upstream side dam-shaped member 6 may be adjusted such that the sizeof the gap t₀ between the top end of the upstream side dam-shaped member6 and the support web W is in the range of 0.1 mm to 3 mm, and inparticular, is in the range of 0.3 mm to 1 mm.

As shown in FIG. 3, the size of the interval between the upstream sidedam-shaped member 6 and the bar 2, i.e., a primary side clearance t1,and the interval between the downstream side dam-shaped member 8 and thebar 2, i.e., a secondary side clearance t2, may each be set to be about0.1 mm to 10 mm. Note that both the upstream side dam-shaped member 6and the downstream side dam-shaped member 8 may be formed such that thedistance between the supporting stand 4 and the upstream side dam-shapedmember 6 and the distance between the supporting stand 4 and thedownstream side dam-shaped member 8 can be adjusted.

An upstream side coating liquid supplying flow path 10, which suppliesthe liquid for forming a plate-making layer to the upstream side of thebar 2, is provided between the supporting stand 4 and the upstream sidedam-shaped member 6. A downstream side coating liquid supplying flowpath 12, which supplies the liquid for forming a plate-making layer tothe downstream side of the bar 2, is provided between the supportingstand 4 and the downstream side dam-shaped member 8.

The upstream side dam-shaped member 6, the supporting stand 4, and thedownstream side dam-shaped member 8 are supported from beneath by a base20 which can be raised and lowered. The base 20 is formed as a shallowbox whose top surface is open, so as to be able to receive and recoverthe liquid for forming a plate-making layer which crosses over theupstream side dam-shaped member 6 and the downstream side dam-shapedmember 8 and flows down. The base 20 has, at the bottom surface thereof,an upstream side liquid supplying conduit 22 which supplies the liquidfor forming a plate-making layer to the upstream side coating liquidsupplying flow path 10, a downstream side liquid supplying conduit 24which supplies the liquid for forming a plate-making layer to thedownstream side coating liquid supplying flow path 12, and a coatingliquid recovery conduit 26 which recovers the liquid for forming aplate-making layer received in the base 20. The upstream side liquidsupplying conduit 22, the downstream side liquid supplying conduit 24,and the coating liquid recovery conduit 26 are all connected to acoating liquid storing tank 30 in which the liquid for forming aplate-making layer is stored.

An upstream side liquid supplying pump 32, which supplies the liquid forforming a plate-making layer which is stored in the coating liquidstoring tank 30 to the upstream side coating liquid supplying flow path10, is provided at the upstream side liquid supplying conduit 22. Adownstream side liquid supplying pump 34, which supplies the liquid forforming a plate-making layer to the downstream side coating liquidsupplying flow path 12, is provided at the downstream side liquidsupplying conduit 24.

A pressing roller 40 is provided at the upstream side of the upstreamside dam-shaped member 6. The pressing roller 40 abuts, from above, theupper surface of the support web W, i.e., the surface at the sideopposite the roughened surface Sg, and presses the support web Wdownward, i.e., toward the bar 2. By increasing and decreasing thepressing force by which the pressing roller 40 presses the support webW, the size of the gap t₀ between the support web W and the upstreamside dam-shaped member 6 can be increased and decreased.

Web holding rollers 50 and 52, which abut the top surface of the supportweb W and hold the support web W such that the support web W is conveyedalong the conveying path T, are disposed at the upstream side anddownstream side of the coating device 100.

Any of smooth bar, grooved bar, and wire bar can be used as the bar 2.As shown in FIG. 1, the coating bar may be driven in the directionopposite to the traveling direction a of the support web W. Or, thecoating bar may be driven in the same direction as the travelingdirection a, or may be slave-rotated.

As shown in FIGS. 1 through 3, the upstream side surface of the upstreamside dam-shaped member 6 is bent, at the upper end portion thereof,toward the downstream side. The downstream side surface is formed in avertical plane shape. Thus, the top end portion of the upstream sidedam-shaped member 6 is formed on the whole as a wedge shape whosethickness decreases toward the top.

The upstream side surface of the downstream side dam-shaped member 8 isformed in a vertical plane shape. The downstream side surface is bent,at the upper end portion thereof, toward the downstream side. Thus, thetop end portion of the downstream side dam-shaped member 8 is formed onthe whole as a wedge shape whose thickness decreases toward the top.

At the coating device 100, the liquid for forming a plate-making layer,which is stored in the coating liquid storing tank 30, is suppliedthrough the upstream side liquid supplying conduit 22 to the upstreamside coating liquid supplying flow path 10, and is supplied to the spaceformed by the support web W and the bar 2 and the upstream sidedam-shaped member 6.

A portion of the liquid for forming a plate-making layer which issupplied to this space is adhered to the roughened surface of thesupport web W by the bar 2. The remainder of the liquid for forming aplate-making layer flows out to the upstream side from the gap t₀between the support web W and the top portion of the upstream sidedam-shaped member 6, flows along the upstream side surface of theupstream side dam-shaped member 6, and flows down into the base 20.

The liquid for forming a plate-making layer, which is supplied to theupstream side coating liquid supplying flow path 10, passes through theprimary side clearance t1, and is supplied to the pool of coating liquidformed by the support web W and the bar 2 and the upstream sidedam-shaped member 6.

The liquid for forming a plate-making layer, which is supplied to thedownstream side coating liquid supplying flow path 12, passes throughthe secondary side clearance t2, is supplied to the downstream side atthe bar 2, overflows to the downstream side along the top surface of thedownstream side dam-shaped member 8, and flows down onto the base 20.

The liquid for forming a plate-making layer, which flows down into thebase 20, returns to the coating liquid storing tank 30 through thecoating liquid recovery conduit 26.

Here, given that the amount of the coating liquid supplied at theupstream side liquid supplying pump 32 is S, the size of the gap t₀ ist₀, the flow rate of the liquid for forming a plate-making layer at thegap t_(o) is V, and the liquid feed width by which the liquid forforming a plate-making layer is fed toward the gap from the upstreamside coating liquid supplying flow path 10 is w, the relationship.V=S/(t ₀ ·w)is established among S, t_(o), V and w. Further, the liquid feed amountS can be determined by a flow meter provided at the exit side of theupstream side liquid supplying pump 32. The size of the gap t₀ can bedetermined by raising the base 20 up to the height at the time ofcarrying out coating of the liquid for forming a plate-making layer, andinserting clearance gauges of various thicknesses into the gap t_(0.)Moreover, the liquid feed width w can be determined by measuring, by ascale or a tape measure or the like, the width by which the liquid forforming a plate-making layer flows out from between the bar 2 and theupstream side dam-shaped member 6.

When the flow rate V is set to 3 m/min or more by adjusting the size ofthe gap t₀ by raising or lowering the pressing bar 40, or by controllingthe liquid feed amount S by raising or lowering the rotational speed ofthe upstream side liquid supplying pump 32 or the degree of opening of athrottle valve (not illustrated) provided at the exit side thereof, theaccompanying air which is brought into the coating device 100 by thesupport web T is pushed out to return to the upstream side by the flowof the liquid for forming a plate-making layer which passes through thegap t₀.

Accordingly, even in cases in which the support web W is conveyed at ahigh speed, the accompanying air at the surface of the support web W iseliminated. Thus, defects such as local absence of the coating liquid orthe like at the coated film can effectively be prevented from arising.

Given that the liquid feed amount of the upstream side liquid supplyingpump 32 is S1, the liquid feed amount of the downstream side liquidsupplying pump 34 is S2, the flow rate of the liquid for forming aplate-making layer at the primary side clearance t1 is V1, the flow rateof the liquid for forming a plate-making layer at the secondary sideclearance t2 is v2, and the liquid feed width by which the liquid forforming a plate-making layer is fed at the upstream side coating liquidsupplying flow path 10 and the downstream side coating liquid supplyingflow path 12 is w, the following relationships are established among S1,S2, t1, t2, v1, v2 and w:v1=S1/t1·w  (1)v2=S2/t2·w  (2)Further, the liquid feed amount S1 and the liquid feed amount S2 can bedetermined by flow meters provided at the exit sides of the upstreamside liquid supplying pump 32 and the downstream side liquid supplyingpump 34. The thicknesses of the primary side clearance t1 and thesecondary side clearance t2 can be determined by inserting clearancegauges of various thicknesses between the bar 2 and the upstream sidedam-shaped member 6, and between the bar 2 and the downstream sidedam-shaped member 8. Moreover, the liquid feed width w can be determinedby measuring, by a scale or a tape measure or the like, the width bywhich the liquid for forming a plate-making layer flows out frombetween, on the one hand, the bar 2 and, on the other hand, the upstreamside dam-shaped member 6 and the downstream side dam-shaped member 8.

When the flow rates v1 and v2 are set to 5 mm/sec or more by adjustingthe thicknesses of the primary side clearance t1 and the secondary sideclearance t2 by making the upstream side dam-shaped member 6 and thedownstream side dam-shaped member 8 approach or move away from thesupport stand 4, or by controlling the liquid feed amounts S1 and S2 byincreasing or reducing the rotational speeds of the upstream side liquidsupplying pump 32 and the downstream side liquid supplying pump 34 orthe degrees of opening of the throttle valves (not illustrated) providedat their exit sides, a uniform and continuous flow of the liquid forforming a plate-making layer is formed at both the upstream sidedam-shaped member 6 and the downstream side dam-shaped member 8.

Accordingly, it is possible to effectively prevent the liquid forforming a plate-making layer from sticking to the top surfaces of theupstream side dam-shaped member 6 and the downstream side dam-shapedmember 8 such that stuck matter arises and the stuck matter adheres tothe coated surface such that various problems in the surface quality(such as coating streaks or the like) arise.

COMPARATIVE EXAMINATION EXAMPLE A (Examples 1 through 3, ComparativeExamples 1 and 2)

One surface of an aluminum web of a width of 800 mm was roughened bybeing successively subjected to brush grain processing, alkali etchingprocessing and electrolytic surface roughening. The one surface was thensubjected to an anodizing treatment such that the support web wasformed.

By using the coating device shown in FIG. 1, a liquid for forming aphotosensitive layer, which served as a liquid for forming aplate-making layer, was coated on the roughened surface Sg of thesupport web, and was dried such that a photosensitive layer was formed.The conditions for coating the photosensitive layer coating liquid wereas follows. Note that, in the present examples and comparative examples,the flow rate V, of the liquid for forming a photosensitive layer, atthe gap t was set by setting the liquid feed amount S of the liquid forforming a photosensitive layer. The size of the gap t was measured byraising the base 20 to the height at the time of coating the liquid forforming a photosensitive layer, and inserting clearance gauges ofvarious thicknesses between the upstream side dam-shaped member 6 andthe support web W. The size of the gap t1 was measured by insertingclearance gauges of various thicknesses between the bar 2 and theupstream side dam-shaped member 6.

a. thickness of support web W 0.3 mm b. conveying speed of 50 m/minsupport web W c. bar coating amount (amount coated onto 20 cc/m² supportweb W by bar 2) d. outer diameter of bar 2 10 mm e. rotational speed ofbar 2 −50 rpm (reverse rotation) f. viscosity of liquid for forming 1mBa a photosensitive layer g. liquid feed amount S1 1.5 liters/min h.liquid feed width w 1000 mm i. outer diameters of pressing 50 mm rollers50 and 52 j. size of primary side 5.0 mm clearance t₁

The results are shown in Table 1. In Table 1 and other tables to bepresented later, “OK” denotes that the occurrence of local absence ofthe coating liquid at the coated surface was not observed, and there isno problem in surface quality. The sign “SOME” denoted that the surfacequality was not good to some extent. The sign “×” denotes that theoccurrence of local absence of the coating liquid was clearly observed.The sign “C. Ex.” means comparative example while the sign “Ex.” meansexample. “Coated surface quality” also stands for the evaluation ofcoating performance of an example or a comparative example.

TABLE 1 flow rate v₁ drying and sticking of at primary liquid forforming a side photosensitive layer on Coated surface clearance t₁primary side dam plate quality C. Ex. 1  3.0 mm/sec x x (i)  C. Ex. 2 4.0 mm/sec SOME x (ii) Ex. 1  5.0 mm/sec OK OK Ex. 2  8.0 mm/sec OK OKEx. 3 10.0 mm/sec OK OK (i) occurrence of coating streaks/adhesion ofstuck matter onto support web. (ii) occurrence of coatingstreaks/adhesion of stuck matter onto support web

As is shown in Table 1, in Examples 1 through 3 in which the flow ratev1, of the liquid for forming a photosensitive material, at the primaryside clearance t1 was 5 mm/sec or more, neither the generation of stuckmatter at the upstream side dam-shaped member 6, nor problems in surfacequality due to the stuck matter adhering to the coated surface of theliquid for forming a photosensitive layer were observed. In ComparativeExamples 3 and 4 in which the flow rate v1 was less than 5 mm/sec, boththe generation of stuck matter and problems in surface quality wereobserved.

COMPARATIVE EXAMINATION EXAMPLE B (Examples 4 through 8, ComparativeExamples 3 through 6)

One surface of an aluminum web of a width of 800 mm was roughenedaccording to the same procedures of the examples 1 through 3. The onesurface was then subjected to an anodizing treatment such that thesupport web was formed.

By using the coating device shown in FIG. 1, a liquid for forming aphotosensitive layer, which served as a liquid for forming aplate-making layer, was coated on the roughened surface Sg of thesupport web, and was dried such that a photosensitive layer was formed.The conditions for coating the photosensitive layer coating liquid wereas follows. Note that, in the present Examples and Comparative Examples,the flow rate V, of the liquid for forming a photosensitive layer, atthe gap t was set by setting the liquid feed amount S of the liquid forforming a photosensitive layer. Further, the size of the gap t wasmeasured by raising the base 20 to the height at the time of coating theliquid for forming a photosensitive layer, and inserting clearancegauges of various thicknesses between the upstream side dam-shapedmember 6 and the support web W. Further, the size of the gap t wasmeasured by inserting clearance gauges of various thicknesses betweenthe bar 2 and the upstream side dam-shaped member 6.

a. thickness of support web W 0.1–0.5 mm b. conveying speed of 50m/min–200 m/min support web W c. bar coating amount (amount coated onto20 cc/m² support web W by bar 2) d. outer diameter of bar 2 10 mm, 15 mme. rotational speed of bar 2 −50 rpm (reverse rotation) f. viscosity ofliquid for forming 10 mBa a photosensitive layer g. outer diameter of 50 mm pressing roller 40 h. distance between central lines of  30 mmpressing roller 40 and bar 2 i. liquid feed amount S 1.0 to 10liters/min j. liquid feed width w 1000 mm k. size of gap t   0.5 mm

The relationship between the liquid feed amount S and the liquid feedwidth w and the gap t was as per following Table 2.

TABLE 2 Gap t = 0.5 mm and Liquid Feed Width w = 1000 mm S (liters/min)V (m/min) 1 2 1.5 3 5 10 10 20

The surface texture of the roughened surface of the support web was 0.5μm according the following measurement. The photosensitive layer formedby the above procedure was removed from the support web. The centralportion of the support web was cut into an appropriate size as aspecimen. The cut central portion was then placed on a platen of asurface texture measuring instrument in a state that the measuringdirection is perpendicular to the rolling direction of aluminum. A 24-mmdistance was measured once to show a result in μm. The instrument wasthe model code 113B made by Tokyo Seimitsu Co., Ltd.

Results of forming a photosensitive layer were tabulated into Table 3 asfollows.

TABLE 3 Flow rate Volume of between dam supplied Conveying plates 6liquid speed Coated surface (m/min) (l/min) (m/min) quality C. Ex. 3 2.01.0  50 OK C. Ex. 4 2.0 1.0 100 x C. Ex. 5 2.0 1.0 100–200 x Ex. 4  3.01.5 100 OK Ex. 5  5.0 1.5 100 OK Ex. 6  10.0 5.0 100 OK Ex. 7  15.0 7.5150 OK Ex. 8  20.0 10.0 150 OK Ex. 9  3.0 1.5 100–200 OK Ex. 10 5.0 2.5100–200 OK Ex. 11 10.0 5.0 100–200 OK Ex. 12 15.0 7.5 100–200 OK Ex. 1320.0 10.0 100–200 OK

As shown in Table 3, in the comparative example 3 in which the flow ratev, of the liquid for forming a photosensitive material, was 2 m/min andconveying speed was 50 m/min, interruption of liquid did not occur, andstable coating was performed. In both of the comparative example 4 inwhich the conveying speed was 100 m/min, and the comparative example 5in which the conveying speed was changed in the range from 100 m/min to200 m/min, the interruption of liquid was observed respectively. In theexamples 4 through 13 in which the flow rate was equal to or faster than3 m/min respectively, no interruption of liquid did occur when theconveying speed was 100 m/min or 150 m/min or even changed in the rangefrom 100 m/min to 200 m/min. Thus, stable coating was performed.

COMPARATIVE EXAMINATION EXAMPLE C (Examples 9 through 13, ComparativeExamples 6 and 7)

Surface roughness was changed in the range from 0.2 to 0.9. Otherconditions to prepare support webs, coat and dry coating liquid forforming a photosensitive layer are the same with those of the examples 4through 13 and the comparative examples 13 through 5. The results aretabulated in Table 4 below.

TABLE 4 Flow rate Volume of between supplied Surface Conveying Coateddam plates liquid Texture speed surface 6 (m/min) (l/mm) (μm) (m/min)quality C. Ex. 6 2.0 1.0 0.2 100–200 OK C. Ex. 7 2.0 1.0 0.5 100–200 xEx. 9 3.0 1.5 0.5 100–200 OK Ex. 10 3.0 1.5 0.7 100–200 OK Ex. 11 10.05.0 0.9 100–200 OK Ex. 12 20.0 10.0 0.9 100–200 OK Ex. 13 20.0 10.0 0.9100–200 OK

As shown in Table 4, in the cases where the flow rate was 2 m/min of theliquid for forming a photosensitive layer, the comparative example 6whose surface roughness of the support web was 0.2 and which isrelatively smoother obtained a well-coated surface. In the comparativeexample 7 in which surface roughness was 0.5, local absence of coatingliquid was clearly observed.

In contrast, in the examples 14 through 18 where the flow rate of thecoating liquid was equal to or faster than 3 m/min, good quality in arespective coated surface was obtained.

COMPARATIVE EXAMINATION EXAMPLE D (Examples 14 through 16, ComparativeExamples 8 through 1-10)

Viscosity of the liquid for forming a photosensitive layer was changedin the range from 0.5 to 50 mPa·s. Other conditions to prepare supportwebs, coat and dry coating liquid for forming a photosensitive layer arethe same with those of the examples 4 through 13 and the comparativeexamples 13 through 5. The results are tabulated in Table 5 below.

TABLE 5 Flow rate between Volume of dam supplied Conveying Coated plates6 liquid Viscosity speed surface (m/min) (l/mm) (mPa · s) (m/min)quality C. Ex. 8 2.0 1.0 0.5–5.0 100–200 OK C. Ex. 9 2.0 1.0 5.0–30 100–200 SOME C. Ex. 10 2.0 1.0 30–50 100–200 x Ex. 14 3.0 1.0 5.0–50 100–200 OK Ex. 15 10.0 5.0 5.0–50  100–200 OK Ex. 16 20. 10.0 5.0–50 100–200 OK

As shown in Table 5, among the comparative examples 8 through 10 whoseflow rate was 2 m/min respectively, the comparative example 8 where arelatively low-viscous coating liquid in the range from 0.5 mPa·s to 5.0mPa·s was used obtained a well-coated surface quality. As the viscosityincreased, local absence of the coating liquid was likely to beobserved. In the comparative example 10 whose viscosity was in the rangefrom 30 mPa·s to 50 mPa·s, local absence of the coating liquid wasclearly observed.

In contrast, in the examples 19 through 21 whose flow rate of the liquidfor forming a photosensitive layer was equal to or faster than 3 m/min,good quality in a coated surface was respectively obtained where theviscosity was in the range from 0.5 mpa·s to 5.0 mpa·s.

COMPARATIVE EXAMINATION EXAMPLE E (Examples 17 through 21, ComparativeExamples 11 through 13)

The frequency of rotation of the bar was changed in this examination.Other conditions to prepare support webs, coat and dry coating liquidfor forming a photosensitive layer are the same with those of theexamples 4 through 13 and the comparative examples 13 through 5. Theresults are tabulated in Table 6 below.

TABLE 6 Flow rate between Volume of Frequency dam supplied of barConveying Coated plates 6 liquid rotation speed surface (m/min) (l/mm)(rpm) (m/min) quality C. Ex. 11 2.0 1.0 +1,590 100~200 OK C. Ex. 12 2.01.0 +700~ 100~200 x +6,360 C. Ex. 13 2.0 1.0 −500~−2, 100~200 SOME+2~+500 Ex. 17 3.0 1.5 −500~−2, 100~200 OK +2~+500 Ex. 18 3.0 1.5−500~−2, 100~200 Excellent +2~+500 Ex. 19 3.0 1.5 −10~−2, 100~200Excellent +2~+10 Ex. 20 10.0 5.0 −500~−2, 100~200 OK +2~+500 Ex. 21 20.010.0 −500~−2, 100~200 OK +2~+500 Note: “+2” = the rotation of 2 rpm inthe support web conveying direction “−2” = the rotation of 2 rpm againstthe support web conveying direction

As shown in Table 6, among the comparative examples 11 through 13 whoserespective flow rate was 2 m/min, the comparative example 11 where thefrequency of rotation of the bar was set to be +1,590 rpm obtained awell-coated surface. In the comparative example 12 where the frequencyof rotation of the bar was changed in the range from +700 rpm to +6,360rpm, local absence of the coating liquid was clearly observed. Also inthe comparative example 13 where the frequency of rotation of the barwas changed in the range from −2 rpm to −500 rpm and +2 rpm to +500 rpm,good quality in a coated surface was not obtained.

In contrast, in the examples whose respective flow rate was 2 m/min,good or excellent quality in a coated surface was obtained respectivelywhere the frequency of rotation was in the ranges from −500 to −2 rpmand from +2 to +500 rpm.

As described above, in accordance with the present invention, there areprovided a coating device and a coating method which, even when coatingis carried out while a strip-shaped body is traveling at high speed, cancarry out stable coating in which defects such as local absence of thecoating liquid at the coated film or the like do not arise.

In accordance with the present invention, drying and sticking does notoccur at the dam-shaped member. Accordingly, a coating device and acoating method, in which problems in surface quality do not arise, areprovided.

1. A coating device comprising: a bar which coats a coating liquid on astrip-shaped body conveyed in a given direction, an upstream sidedam-shaped member disposed at an upstream side of the bar so as to facethe bar, the coating device carrying out coating by supplying thecoating liquid from between the upstream side dam-shaped member and thebar, means for setting a flow rate of the coating liquid passing througha gap between the bar and the upstream side dam-shaped member to be 5mm/sec or more, and a downstream side dam-shaped member disposed at adownstream side of the bar so as to face the bar, wherein the flow rateof the coating liquid both at a primary side clearance which is the gapbetween the bar and the upstream side dam-shaped member, and at asecondary side clearance which is a gap between the bar and thedownstream side dam-shaped member, is set to be 5 mm/sec or more.
 2. Thecoating device of claim 1, wherein the gap between the bar and theupstream side dam-shaped member is a value in a range of greater than0.1 mm and less than 10 mm.
 3. The coating device of claim 1, whereinthe bar rotates at a circumferential speed which is equal to a conveyingspeed of the strip-shaped body.
 4. The coating device of claim 1,wherein the bar rotates at a circumferential speed which different thana conveying speed of the strip-shaped body.
 5. The coating device ofclaim 4, wherein the bar rotates in a direction opposite to the conveyeddirection of the strip-shaped body.
 6. The coating device of claim 1,wherein each of the upstream and downstream dam-shaped members is arectangular plate.
 7. The coating device of claim 1, wherein thestrip-shaped body is a flexible base material.
 8. The coating device ofclaim 1, further comprising a base which supports the dam-shaped membersfrom beneath, and the base is box-shaped.